Star Trek: The Next Generation, The Best of Both Worlds and The Best of Both Worlds, Part II. First aired June 18, 1990 and Sept. 24, 1990.
Although the franchise has been praised for liberal virtues like diversity and a commitment to social justice, life on starships is fiercely hierarchical: you do what the captain says. This two-parter The Next Generation's third-season cliffhanger and fourth-season premiere not only remove the captain from the equation (a device common to many lesser episodes) but actually make him an enemy. And not just any enemy, but the best enemy that Star Trekwriters ever conceived: Captain Picard becomes Locutus, a leader of the Borg, the part-organic, part-mechanical space zombies with the fantastic motto "Resistance is futile." Picard's body is mangled with Borg implants; his brain, thoroughly washed. The Enterprise crew must get him back lest his expertise be used to destroy Earth. Data ends up linking his android brain to Picard in order to save the captain an echo of Spock's mind-melding with Kirk. Over the life of The Next Generation, the Data-Picard friendship eventually becomes as poignant as the Spock-Kirk bromance. (May I point out that females do not seem central to any of their lives?) A final note: These episodes were among the first to show that real-life technology had advanced enough to create a feature-length digital effects TV show that didn't look chintzy.